Why a Canadian marijuana possession amnesty is harder to implement than it sounds

As legalization of recreational cannabis comes closer to being a reality, the federal Liberals are coming under pressure to clear the criminal records of those convicted of marijuana offences in the past.

Last week, Public Safety Minister Ralph Goodale sounded open to the possibility, saying that the government was “weighing all of the legal implications to make sure that we fully understand all the dimensions of this and, when we’re in a position to make an announcement, we will do so.”

Last April, Prime Minister Justin Trudeau said his government would “take steps to look at what we can do for those folks who have criminal records for something that would no longer be criminal … We will move forward in a thoughtful way on fixing past wrongs that happened because of this erroneous law that I didn’t put in place and that I’m working hard to fix.”

In theory, Ottawa should be able to erase Canadians’ records for marijuana possession by just telling the programmers to do it. In 2014, for example, RCMP data experts destroyed all copies of the long gun registry outside Quebec in a four-day process.

However, the structure of the RCMP’s national criminal record databases makes it difficult to consistently pick out records related to marijuana from those for other drugs. That means that erasing marijuana possession (or trafficking) records could turn into a painstaking, manual process, involving searches in court and police archives across the country.

WATCH: Public Safety Minister Ralph Goodale told reporters in London, Ontario Friday morning that for years Canada’s marijuana laws were ineffective, and the Trudeau Liberals are simply making changes that were long overdue and needed.

The problem is that while police forces can enter the type of drug someone is charged with possessing into data which is sent to the RCMP, they don’t have to and often don’t, the force told Global News last May. So a record can show whether someone has a record for possessing an illegal drug, but not necessarily which one.

As well, someone found with a small amount of pot could be charged under one of two sections of the Controlled Drugs and Substances Act, one of which relates to marijuana specifically, and one of which is more generic.

The principle seems clear, but the problem is that some acts for which people were convicted of — old offences like buggery and gross indecency — were consensual and others weren’t. And there’s no way to tell the difference just by looking at the RCMP’s criminal database.